Quick question for those who may have been in a similar situation. CA is running late and as soon as I sit down the plane is already on ground power and hotter than Juarez. I figure I'll start it up and get the plane cooling off... except the fueler is just getting hooked up and doing his business (large uplift for DFW with an alternate so this is going to take a little while). My understanding is that we aren't supposed to change electrical sources during fueling, but are we also precluded from deselecting the APU gen and spinning it for the packs while fueling and leaving it on the GPU until that's taken care of?

I opted not to start it and if there's nothing against doing so, that decision will haunt me for the rest of my days.